Solenoid operated valves



July 30, 1957 w. E. RENICK ETAL souanom OPERATED VALVES Filed Oct. 5,1953 A. C. LINE A. 0. LINE INVENTORS Ki UNIT (2. 6000M y weuum EJIENUCKSOLENOID OPERATED VALVES Wendell E. Renick and Kenneth C. Goodman,Columbus, Ohio, assignors, by mesne assignments, to American Brake ShoeCompany, New York, N. Y., a corporation of Delaware Application October5, 1953, Serial No. 384,078

4 Claims. (Cl. 317-123) This invention relates generally to hydraulicsand more particularly to valves of the electrically actuated typesometimes designated in the trade as solenoid operated valves.

Solenoid operated valves generally have a spool element which slidesback and forth in a bore to control communication between ports in thevalve casing. When these valves are employed to govern fluid under highpressures, there is a tendency, particularly noticeable when the valveshave remained in a specific flow directing condition for prolongedperiods, for the spool element to stick-and fail to move when thesolenoid is energized. If the condition is not remedied in due time thesolenoid may overheat or burn out and require replacement. The reasonsfor the sticking of the spool are not fully known but it has been foundthat a sticking spool may be jarred loose through the application of animpulse of greater magnitude than the force required to move it undernormal operating condition. It has been found also that a solenoid of asize sufiicient to exert the additional force necessary to move a spoolwhen it sticks is generally excessive in size and impractical to supplysince the additional force is only needed occasionally and then only fora short time. The present invention is partially based on the theorythat a solenoid designed to operate at a given A. C. voltage to producea predetermined force has a coil which will produce approximately thesame force when a D. C. voltage equal to one-fourth the given A. C.voltage is applied or a force greater than such predetermined force whena D. C. voltage equal to the given A. C. voltage is applied. It is, ofcourse, obvious that the coil would burn out if such D. C. voltage weresustained, therefore, it is an object of this invention to provide meansfor momentarily applying a large D. C.

voltage to the coil to cause it to'exert a surge of force of increasedintensity without the use of a large power source. 7

An object of this invention is to provide solenoid means for operating ahydraulic valve and to provide means for energizing such solenoid meansto cause it to initially apply an impulse of considerable force to thespool element of the valve to jar it loose from a sticking condition andthen apply a sustained force of normal magnitude to the freed spool tomove it to and retain it in the desired position.

Another object of the invention is to provide electrical .means forcausing a solenoid of predetermined capacity to momentarily exert aforce of multiplied intensity to free the sticking spool then exert itsnormal force to move the freed spool.

A further object of the invention is to provide a hydraulic controlvalve having one or more solenoids for operating the valve, eachsolenoid being designed to operate at a predetermined alternatingcurrent voltage to produce a desired force and providing an electriccontrol circuit having a capacitor discharge means for momentarilyapplying a direct current voltage of predetermined magnitude to thesolenoid coil, the direct current voltage United States Patent PatentedJuly 30, 1957 serving to multiply the force exerted by the solenoid, thecircuit being designed to apply the direct current voltage onlymomentarily to prevent injury to the solenoid and then apply thealternating current voltage to cause normal operation after the directcurrent charge has restored the valve to normal operating condition.

A still further object of the invention is to provide a hydrauliccontrol valve having alternating current solenoids for effecting itsoperation and electrical means for operating the solenoids, theelectrical means having a control circuit for each solenoid and meansfor converting alternating current to direct current and storing thesame, the control circuits having relay means for momentarily applying acharge of direct current to a selected solenoid to cause it to exert apredetermined force on a movable element of the valve then continuouslyapply alternating current to the solenoid to cause normal operation, therelay means also serving, when the application of the alternatingcurrent is interrupted, to momentarily apply another charge of directcurrent to another solenoid to free the movable element of the valve sothat it may assume another position under normal operation.

Another object of the invention is to provide a hydraulic control valveand solenoid operating mechanism of the type mentioned in the foregoingparagraph with a rectifier and condenser combination known in the tradeas a cascade voltage doubler by means of which alter nating current isconverted to direct current of substantially double magnitude and storedin the condenser means to be applied at the proper instant to thesolenoid and relay coils to effect desired results, it having been foundthat, by converting the alternating current and increasing themagnitude, a multiplied force may be developed in the solenoid coil towhich it is applied, resistor means being provided to limit theapplication of the converted current to the solenoid coils to preventpremature deterioration thereof.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred form of embodiment of the invention isclearly shown.

In the drawings:

Fig. 1 is a diagrammatic view illustrating one example of a capacitordischarge portion of an electrical system which capacitor dischargeportion may be used to convert alternating current to direct current andmomentarily apply direct current impulses to solenoids employed inoperating a hydraulic valve; and v Fig. 2 is a diagrammatic view of anelectrical circuit embodying a modified capacitor discharge system foroperating a double solenoid control valve.

In the drawings, the numeral 20 designates generally the simple form ofcapacitor discharge system shown in Fig. 1 which may be used in anelectrical circuit. In the system shown in Fig. 1 leads 21 and 22 areprovided to connect the illustration to an alternating current powersource. In this system, the coils of the solenoids are indicated by thenumerals 23 and 24. The system also includes a condenser 25 and 26 and aresistance element 27, 28 for each coil. The system further includes arectifier, indicated by the numeral 30, one terminal of the rectifierbeing connected with one of the alternating current leads 21. The otherterminal of the rectifier is connected by leads 31 and 32 with theresistance elements, these also being connected by lines 33 and 34 withone terminal of the condensers 25 and 26. The other terminals of thesecondensers are connected by lines 35 and 36 with on terminal of thecoils 23 and 24, the other terminals being connected by the lines 37 and38 with the other alternating current conductor 22. This conductor isalso connected by a line 40 with a selector switch 41, the switch beingshown in Fig. l in an off position. This switch may be moved in eitherof two directions to momentarily connect line 33 01134 with line 40.When the system is connected with the alternating current power source;the rectiiier will convert the alternating current to directcurrent andthe condensers and 26 will be charged with this direct current, the rateof the charging current being determined by the resistance elements 27and 28. When the selector swtich is moved to connect eitherline 33 orline 34 with lines and 3'7 or 38, respectively, the respective condenser25 or 26 will be connected with its associated coil 23 or 24. The directcurrent stored in the condenser will then be discharged into the coil tomomentarily energize it and cause it to exert an operatingforce on thecore, not shown, of the solenoid. The switch 41 is only closedmomentarily since the current stored in the condenser connected with therespective coil will be quickly dissipated.

It. will be obvious that the size of the valve to be operated willdetermine the power requirements of the solenoids used to elfect itsoperation. It will also be obvious to one skilled in the art that thesolenoids and power source utilized will determine the ratings of therectifier 30, the condensers or capacitors 25 and 26 and the currentlimiting or isolation resistors 27 and 28. An example of a group ofparts found suitable for use with one valve designed for operation by110 volt A. C. solenoids and 110 volt A. C. power is as follows: Therectifier 35) may be of any suitable type, such as a selenium rectifier,and have a rating of one ampere at 110 volts. The condensers 25 and 26have a capacitance of 200 microfarads with a rating of approximately4-50 volts D. C. And the isolation resistors 27 and 28 have a rating ofone thousand ohms resistance with a power of 50 watts. With the systemconnected to a 110 volt A. C. source, as shown, the rectifier convertsthe applied alternating voltage to D. C. voltage in the usual manner andthis D. C. voltage is stored in the capacitors 25 and 26. The energystored is determined by the amount of capacitance 25 and 26, which inthe above example is approximately lSO volts D. C., at 22 /2watt-seconds. It will be seen that the instant the switch 41 isconnected with the line 34 the energy stored in capacitor 26 will bedischarged into the coil 24. The voltage stored in the capacitor 26 willbe quickly exhausted, but, since the charge is D. C. voltage, thepowerdeveloped will be substantially four times that normally developed bythe solenoid and will be sufiicient to jar the spool loose from asticking position. After the spool is loosened, it may easily be movedwith the normal] 10 volt A. C. supply.

In the circuit shown diagrammatically in Fig. 2 a modified form ofcapacitor discharge system is used to apply an impulse of increasedintensity to the solenoids of the hydraulic valve indicated at 42. Thevalve 42 is of substantially conventional construction and includes acasing 43 having a plurality of ports, not shown. The casing alsoincludes a bore for slidably receiving a spool valve element whichserves in various positions to connect certain sets of the ports in thecasing. The spool also has projections 45 and 46 which extend intosolenoid coils 47 and 48, these extensions functioning as cores for thesolenoids and being attracted by the forces exerted by the coils whenthey are energized. When these forces are applied to the extensions, thevalve spool is moved from a centered position to one end or the other ofthe valve casing. The control valve and solenoids are substantiallyconventional in construction and further description thereof isunnecessary.

The invention resides in the adaptation of a capacitor discharge systemto the electrical control circuit for the solenoids. The invention alsocomprises the provision of electrical means for converting thealternating current supplied from a suitable source into direct currentof greater magnitude and momentarily applying this current to thesolenoids at the proper time to cause them to exert a force equal to thenormal designed force multiplied a predetermined number of times, toimpart a jarring impulse to the valve spool to loosen it from a stickingcondition so that it may then be moved by the normal force of thesolenoid. The means chosen to illustrate the conversion of thealternating current to direct current of higher voltage comprises anelectrical device known in the trade as a cascade voltage doubler of thehalf wave type. It is an electrical device commonly used in electronicwork to obtain a D. C. voltage which is higher than a given A. C. input.

This device includes a plurality of rectifiers and condensers connectedin a certain manner shown diagrammatically in Fig. 2. This cascadevoltage doubler is connected with an alternating current line indicatedgenerally by the numeral 5%, the other alternating current line beingdesignated by the numeral 51. A main switch 52 is disposed in line '50to control the connection of the cascade voltage doubler, indicatedgenerally by the numeral 53, with the alternating current source. Aresistance 54 is also arranged between the voltage doubler and line 50.Line 51 is'connected by lines 55, 56 and 57 with the second terminal ofthe voltage doubler. Voltage doubler 53ir'1cludes a condenser 53A, withwhich A. C. supply line '50 is connected through resistor 54, and a pairof rectifiers 64 and 65 which are oppositely arranged, rectifier 64being connected between condenser 53A and line 57 while rectifier 65 isconnected between condenser 53A and a second condenser 53B which is inturn connected with line 57. The line 57 is connected through lines 56and 55, with A. C. supply line 51. When switch 52 is closed, thecondenser 53A is charged through one rectifier with the peak voltage onone-half of the cycle and this voltage is then added in series on thenext half cycle to the voltage charge to condenser 53B through the otherrectifier. Condenser 53B is thus charged with twice the peak voltage'ofthe A. C. input. Condensers 66, 67, 68 and 69 are connected in parallelthrough current limiting resistors with condenser 53B and are chargedtherefrom with the capacitance required to do the particular job forwhich they have been provided.

The electricalsystemshown in Fig. 2 has a control section for eachsolenoid, the section controlling solenoid 47 being indicated generallyby the numeral 58 whilenumeral 60 designates the section controlling thesolenoid 43. These control sections are substantially duplicates, eachhaving first, second and third relays indicated by the numerals 61, 62and 63, respectively.

The first'relay No. 61in each control circuit includes three switchesdesignated, respectively, by the numerals 70, 71 and 72. The secondrelay in each control circuit includes two switches "73 and 74 while thethird relay has a single switch 75. A selector switch 76 is provided toconnect either of the control circuits 58 or 60 with thealternating'current power supply. Ahead 77 extends from the switch 76 tothe control system 60 while a lead'7 8 extends from the switch to theother control system 58. Since the control circuits for each solenoidare identical, a description of section 60 only will be made at thistime to simplify the description and facilitate an understanding of theinvention.

It will be noted that switch 70 of the first relay 61 is atwo-positionswitch and, when the relay 61 is de-energized, will be in aposition to establish a connection between line 77 and -a line 80 whichleads to the coil of the second relay 62, this coil being connected bylines 81 and 55 with the second alternating current lead 51.

' It will be obvious that, when the main switch-52 is closed and theselector switch'76moved to a' position to connect lead 77 withalternating current lead 50, the coil'of the second relay 62 will beenergized. When this coil is energized switches 73 and 74, which arenormally open switches, will be moved to closed positions. Switch 74will then complete a circuit from condenser 67, in which a directcurrent charge has been stored, to the coil 48,

. this circuit including lines 82, 83, 84, 85 and 86. The instant switch74 is moved to a closed position, the current stored in condenser 67will be applied to the solenoid coil 48. Since this current is a directcurrent and of twice the capacity of the alternating current source, theforce exerted by the coil 48 will be a number of times the normal forceand will, therefore, impart a severe jolt or jar to the core associatedwith the coil, this core transmitting the jar to the valve spool. If thespool is in a sticking condition before the jar is applied thereto, itwill be forced loose by the power applied by the direct current chargeto the coil. This charge will be momentarily applied, however, and willhave no deleterious effect on the coil.

When switch 73 of the second relay moves to a closed position, it willconnect the coil of the relay 61 with the alternating current sourcecausing this coil to actuate the three switches 70, 71 and 72 forming apart of relay 61. When switch 70 is moved, relay coil 62 will bedisconnected from the alternating current source and switches 73 and 74will move to an open position. Although switch 73 moves to an openposition, current will continue to flow to relay 61 through switch 70 ofthis relay. The relay will remain energized as long as the selectorswitch 76 is held in position to connect line 77 with alternatingcurrent line 59. Switch 70 completes the holding circuit for relay 63..The switch 71, when in a closed position, completes the circuit from thealternating current power source to the solenoid coil 48, this circuitbeing completed through line 77, switch 71 and lines 87, S5 and 86. Theflow of normal operating current to the solenoid 48 will continue aslong as relay 61 is energized. As usual in solenoid operated valves, theenergization of solenoid 48 will cause the spool element to move to apredetermined position to establish communication between certain setsof the ports in the valve casing. This communication will be maintainedas long as the solenoid 48 is energized.

In some instances, solenoid controlled valves are spring biased toward apredetermined position, one example being a four-way valve in which thespool occupies a centered position when the solenoids are de-energized.It has been found that, in some instances, particularly when the valvesare operated at high pressures, the spool may stick after having beenretained in a predetermined position for a sustained period. It is,therefore, another object of this invention to impart to the spool aforce impulse of high intensity applied to urge the spool in theopposite direction from the force previously applied. To carry out thisobject, the third relay 63 has been provided in each control circuit.However, the operation of the relay 63 in each control section isgoverned by the switch 72 of the relay 61 in the other control section.Switch '72 is a normally closed switch, that is, it is closed when therelay coil is de-energized. When the coil of the relay is energized, theswitch 72 is held in an open position. Then, following the movement ofthe selector switch 76 to an otf position, the switch 72 will return toits closed position and will complete the connection of a condenser 69through lines 88 and 90 to the coil of the third relay 63 of the othercontrol circuit, this relay being connected by lines 55, 56 and 57 withthe second terminal of the condenser 69.

When the coii of the third relay is so connected, direct currentpreviously stored in the condenser 69 will flow through the coil of thethird relay 63 energizing this coil and closing switch 75. When thisswitch is closed, direct current from another condenser 66 will flowthrough lines 93 and 92, switch 75 and line 93 to the coil of thesolenoid 47, this being the solenoid for moving the spool in theopposite direction to that in which it is moved by the coil 43. Theelectrical impulse from condenser 66 transmitted by the closing ofswitch 75 is a direct current impulse of greater magnitude which willcause the Coil to impart a sharp thrust to the spool which will dislodgethe spool in the'event ithas a tendency to stick; After this sharpthrust loosens the spool, it is returned to a normal centered positionby the spring force in the conventional manner.

If the selector switch is moved in the opposite direction, that is, toconnect lead 78 with the alternating current line 50, the other controlcircuit will be energized to cause the solenoid valve to move in theopposite direction. This control circuit works in the same manner as thecontrol circuit 60, the switch 70 of the first relay providing for theoperation of the second relay 62 which applies a charge of directcurrent from condenser 66 to the solenoid 47 then interrupts this flowof direct current and actuates relay 61 to effect the flow of normaloperating current to the solenoid. Then, when the selector switch isopen, the switch 72 completes a circuit for the coil of the third relayin the other control circuit elfecting a closing of the switch 75 ofthis relay which then effects a momentary fiow of direct current fromcondenser 67 to the solenoid- 48 controlled by the latter circuit, thissolenoid serving to free to spool in the event it is in a stickingcondition. The spool may then return to its normal inoperative position.

From the foregoing, it will be obvious that a conventional solenoidoperated valve having the customary alternating current source and onand oif selector switch has been provided with an electric circuithaving means automatically operative to impart a charge of directcurrent to the solenoid immediately prior to the connection of thealternating current source with the solenoid, the direct current chargeserving to free a movable element of the valve so that it may movenormally when the alternating current is supplied thereto. It will alsobe apparent that the circuit has been so designed that, after onesolenoid of a double solenoid valve has been energized to dispose themovable element of the valve in one position and it is desired to returnthe element to a normal position, a charge of direct current will beimparted to the other solenoid to free the movable element from apossible sticking condition so that it may then return to normalposition in the usual manner. These results are secured withoutrequiring the operator to exert any additional effort or pay any furtherattention to the mechanism.

While the form of embodiment of the present invention as hereindisclosed constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimswhich follow:

We claim:

1. In a solenoid operated valve, a source of alternating current;rectifier means connected with said alternating current source andoperating to change alternating current to direct current; condensermeans in circuit with said rectifier means to store a charge of directcurrent converted thereby; a pair of relays arranged in a circuitincluding the coil of said solenoid, said alternating current source,said rectifier means and said condenser, the first relay of said pairhaving a normally closed switch in circuit with the field coil of thesecond relay, the latter relay having a pair of normally open switches,one of which is connected with the field coil of the first relay and theother connected with said condenser and the coil of said solenoid, thefirst relay having a normally open switch connected with saidalternating current source and the coil of said solenoid; and an on andoff switch in the circuit between said alternating current source andsaid relays, the closing of said on and off switch serving to energizethe field coil of the second relay to complete the connection of saidcondenser with the field coil of said solenoid and the energizing of thefield coil of said first relay, the energizing of the latter relayserving to de-energize the second relay and complete the connection ofsaid alternating current source with the field coil:

of said solenoid.

with said alternating current source and operating to change alternatingcurrent to direct current; condenser means in circuit with saidrectifier means to store charges of direct current converted by saidrectifier; a control circuit for each solenoid, each control circuithaving a set of relay means with first and second relays, the firstrelay having a normally closed switch connected with the field coil ofthe second relay, the second relay having a pair of normally openswitches, one of which is connected with the field coil of the firstrelay and the other of which is connected with said condenser means andthe field coil of the solenoid in the respective control circuit; anormally open switch on said first relay connected with said alternatingcurrent source and the coil of said solenoid; and an on and off switchbetween said alternating current source and said control circuits, saidswitch serving to selectively energize the field coils of the secondrelays in the control circuits to close the open switches of such relaysto momentarily complete the connection of said condenser means with thefield coil of the respective solenoid then energize the field coil ofthe first relay to open the normally closed switch thereof tode-energize the field coil of the second relay and close the normallyopen .switch of said first relay to complete the connection of saidalternating current source with the field coil of the respectivesolenoid.

3. In a solenoid operated valve, first and second solenoids; a source ofalternating current; rectifier means connected with said alternatingcurrent source and operating to change alternating current to directcurrent; condenser means in circuit with said rectifier means to storecharges of direct current converted by said rectifier; a control circuitfor each solenoid, each control circuit having a set of relay means withfirst, second and third relays, the first relay having a normally closedswitch connected with the field coil of the second relay, the secondrelay having a pair of normally open switches, one being connected withthe field coil of the first relay and the other being connected withsaid condenser means and the field coil of the solenoid in therespective control circuit; a selector switch between said alternatingcurrent source and said control circuits, said switch serving toselectively connect either control circuit to said alternating currentsource to energize the field coil of the second relay in the controlcircuit selected and close the open switches thereof to momentarilycomplete the connection of said condenser means with the field coil ofthe respective solenoid then energize the field coil of the first relayto open the normally closed switch thereof to de-energize the field coilof the second relay; a normally open switch on said first relayconnected with the coil of the respective solenoid, said switch beingclosed when the field coil of the first relay is energized to connectthe respective solenoid coil with said alternating current source; asecond normally closed switch on said first relay, said switch beingconnected with said condenser means and the field coil of the thirdrelay in the other control circuit, said second normally closed switchbeing opened when the field coil of the first relay is energized; and anormally open switch on the third relay in each control circuit, saidnormally open switches being connected with said condenser means and thefield coil of the solenoid in the respective control circuit; theopening of said selector switch serving to deenergize the field coil ofsaid first relay and effect the closing of the second normally closedswitch thereof, the closing of this switch momentarily energizing thefield coil of the third relay of the other control system to close thenormally open switch of such third relay and momentarily energize thefield coil of the solenoid in the other control circuit with directcurrent from said condenser means.

4. In a solenoid operated valve, a pair of solenoids; a source ofalternating current; a cascade voltage doubler connected with saidalternating current source, said cascade voltage doubler convertingalternating current into direct current of substantially increasedmagnitude; condenser means for storing charges of direct currentconverted by said cascade voltage doubler; a control circuit for eachsolenoid, each control circuit having a series of relays; a selectorswitch between said control circuits and said alternating currentsource, said selector switch serving to connect either of said controlcircuits with said alternating current source, said relays having switchelements operative when said selector switch is actuated to connect apredetermined control circuit with said alternating current source tosequentially connect the solenoid of the respective control circuit withsaid condenser means to receive a charge of direct current then with thesource of alternating current to receive current therefrom and, uponopening movement of said selector switch, to connect the solenoid of theother control circuit with said condenser means to apply a charge ofdirect current to such solenoid.

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